Bottom Line:
Although reported to be rare, in fact it seems to be more common than previously thought.It has characteristic appearances on plain x-rays, ultrasound, and CT imaging particularly in the prone and supine positions.In this paper, a series of cases is presented outlining its characteristic features and reviewing the relevant literature.

ABSTRACTMilk of calcium (MOC) is a colloidal suspension of calcium salts occurring in calyceal cysts and diverticula. Although reported to be rare, in fact it seems to be more common than previously thought. It has characteristic appearances on plain x-rays, ultrasound, and CT imaging particularly in the prone and supine positions. Often entirely asymptomatic, its appearance may be mistaken for renal stones on radiography or angiomyolipomas on ultrasonography. In this paper, a series of cases is presented outlining its characteristic features and reviewing the relevant literature.

Figure 0004: Prone non-contrast CT scan. Left kidney: Low attenuation cyst in the anterior cortex of the left kidney demonstrating layering out of milk of calcium (MOC) in the prone position.

Mentions:
A 55-year-old man presented with right renal colic and macroscopic hematuria. He subsequently passed a small stone with resolution of his symptoms. An IVU was performed, the right kidney and ureter were normal but an incidental 1.0 cm radiopaque density was noted in the left renal pelvis. USG revealed a left parapelvic cystic structure measuring 2.4 cm in diameter, containing a 1.3cm focus of calcification within its lateral margins. CT demonstrated a 14 mm left parapelvic cyst showing no significant enhancement (-2 to -3 Hounsfield units) with characteristic layering in a dependent fashion, apparent in both the supine and prone images consistent with MOC cysts (Fig. 4).

Figure 0004: Prone non-contrast CT scan. Left kidney: Low attenuation cyst in the anterior cortex of the left kidney demonstrating layering out of milk of calcium (MOC) in the prone position.

Mentions:
A 55-year-old man presented with right renal colic and macroscopic hematuria. He subsequently passed a small stone with resolution of his symptoms. An IVU was performed, the right kidney and ureter were normal but an incidental 1.0 cm radiopaque density was noted in the left renal pelvis. USG revealed a left parapelvic cystic structure measuring 2.4 cm in diameter, containing a 1.3cm focus of calcification within its lateral margins. CT demonstrated a 14 mm left parapelvic cyst showing no significant enhancement (-2 to -3 Hounsfield units) with characteristic layering in a dependent fashion, apparent in both the supine and prone images consistent with MOC cysts (Fig. 4).

Bottom Line:
Although reported to be rare, in fact it seems to be more common than previously thought.It has characteristic appearances on plain x-rays, ultrasound, and CT imaging particularly in the prone and supine positions.In this paper, a series of cases is presented outlining its characteristic features and reviewing the relevant literature.

ABSTRACTMilk of calcium (MOC) is a colloidal suspension of calcium salts occurring in calyceal cysts and diverticula. Although reported to be rare, in fact it seems to be more common than previously thought. It has characteristic appearances on plain x-rays, ultrasound, and CT imaging particularly in the prone and supine positions. Often entirely asymptomatic, its appearance may be mistaken for renal stones on radiography or angiomyolipomas on ultrasonography. In this paper, a series of cases is presented outlining its characteristic features and reviewing the relevant literature.